The present invention relates generally to hollow needles, and, more particularly, to the needle portion of hypodermic needles and the like for penetrating various tissues to inject drugs, medicine, etc., to implant conductor wires or other similar structures or to carry out any other appropriate biomedical function.
It is, of course, well known that great progress continues to be made in the medical sciences. New drugs are constantly being developed to treat or cure diseases, and medical problems once thought to be incurable are now routinely treated. Moreover, surgical techniques have reached such a high level of advancement and sophistication that there almost seems to be no limit to the type of tissue repair which can be achieved.
However, in all the years of progress in medicine, there has been virtually no change in one of the principal tools of the medical profession--the hypodermic needle. Basically, the hypodermic needle includes a relatively thin, straight, hollow tube coupled at one end to a syringe of one type or another. The other end is formed with a bevel of about 17.degree. to form a sharp point, with the leading tip of the needle point being along the longest side of the needle tube.
The hypodermic needle has always performed its function of injecting drugs, medication or the like into the desired subcutaneous tissue. However, there is one universally recognized drawback to the hypodermic needle as it is currently constructed. A certain degree of trauma is suffered by the tissue(s) penetrated by the needle, due to tissue coring and/or shaving.
Thus, in conventional needles with the usual beveled tip, the coring effect results in a plug-like piece of tissue being cut-out and becoming wedged inside the needle tube. In addition, the shaving effect caused by the sharp recessed edge of the needle point (sometimes called the heel of the bevel) results in thin slices of tissue being cut during penetration and becoming lodged in the needle tube. For needles of very small tube diameter, the trauma often causes only a little discomfort, usually in the form of a dull pain which lasts a day or so after the injection. However, the larger the needle size, the greater the trauma, particularly that resulting from coring.
The tissue core and shavings will be ejected from the needle tube when fluid is released from the syringe, so they do not usually interfere with the fluid injection. However, it has recently been suspected that as these discharged tissue particles decompose, particularly when injected into the blood stream, there is a risk of developing certain types of cancer.
One design for eliminating the tissue coring and shaving effects, particularly in larger needles, involves placing a sharply pointed rod (often called an obturator) inside the needle tube with the sharp end of the obturator projecting beyond the tip of the needle (which need not, therefore, be beveled to form a sharp point). The obturator fairly well blocks the hollow needle tube during penetration by the needle, and is removed once the needle tip is at the desired depth in the tissue. However, this arrangement entails the extra expense of fabricating the obturator to fit the needle tube. Furthermore, in use, it necessarily involves the additional steps of removing the rod and safely coupling the syringe to the needle tube, and, when used in coronary assist procedures, inserting a pacer wire (i.e., a helio coid) or other conductor wire through the needle tube. In emergency or critical procedures, the time lost by performing these additional steps could be critical.
Accordingly, it is an object of the present invention to provide new and improved needle structures for hypodermic needles and the like and methods for making a needle. It is another object of the invention to provide new and improved needle structures for hypodermic needles and the like, and methods for making a needle, which is capable of easier penetration into a patient's tissue with minimum trauma.
It is also an object of the invention to provide new and improved needle structures for hypodermic needles and the like, and methods for making a needle, which substantially reduces and can virtually eliminate the coring and shaving effects experienced with conventional hypodermic needle constructions. Furthermore, the present invention is intended to be capable of embodiment in virtually any size needle for uses ranging from routine injections to precision injection/implantations such as in coronary assist procedures. In addition, the needle of the present invention can be embodied in otherwise conventional needle structures.
Objects and advantages of the invention are set forth in part herein and in part will be appreciated herefrom. However, these and other objects and advantages of the invention may be learned through practice with the invention, the same being realized by means of the structures, instrumentalities, steps, methods and combinations disclosed and claimed herein. The invention thus resides in the novel constructions, arrangements, steps, operations, combinations and improvements herein shown and described.